The invention relates to a device for dewatering solid/liquid suspensions especially pulp suspensions, where the suspension is dewatered between two belts, one dewatering zone being designed as wedge zone.
This type of device is known, for instance, from AT 402.517. To achieve a high dryness, so-called S-module rolls with area pressing are used here, and subsequently also several press nips with line pressing. Due to the multiplicity of deflection and press rolls, the machine is comparatively long.
The aim of the invention is, therefore, to simplify the known device and to achieve a shorter and more compact design and thus to reduce costs.
According to the invention, this is achieved by the pair of rolls following the wedge zone imparting both area pressure and line pressure on the pulp web formed by the pulp suspension. By combining the S-module rolls imparting the area pressure with a press nip with line pressing force two rolls can be done without, which gives a far shorter and more compact design. With fewer rolls and bearings, costs can be saved.
An advantageous design of the invention is characterized by the wedge height at the outlet end, especially over the entire web width, being adjustable in its height. This allows production of the most varied basis weights.
A favorable advancement of the invention is characterized by the first combined deflection and press roll of the pair of rolls being arranged below the end of the wedge zone and directly adjacent to it, with the wedge zone possibly being extended beyond the first subsequent combined deflection and press roll and the opposite part reaching into the gap between the wire belt and the roll. This further shortens the machine, whereby through this design the pulp web between the wires is stabilized as far as into the first combined deflection and press roll, preventing the fibers from being shoved back and subsequently also lateral squeezing out of the pulp material ahead of the S-module and the press nip. Also, this prevents subsequent stretching of the kilter cake and thus re-wetting. Especially with hard to dewater material, the throughput performance of the dewatering unit is thereby increased.
An advantageous advancement of the invention is characterized by the wrap angle of the first combined deflection and press roll being between 10 and 90 degrees, preferably approximately 60 degrees.
An further advancement of the invention is characterized by the wrap angle of the second combined deflection and press roll being between 30 and 120 degrees, preferably approximately 100 degrees.
An advantageous development of the invention is characterized by the wrap angle/e being changeable, especially adjustable.
A favorable design of the invention is characterized by only one upper and/or lower deflection roll at the beginning of the wedge being in each case provided as stretcher roll immediately at the beginning of the wedge. This means that further rolls can be saved, which causes the system to be shortened accordingly and leads to essential cost savings.
A favorable advancement of the invention is characterized by the upper part of the wedge being especially automatically adjustable, for instance, elastically and by the opposite part being fixed.